Haloarchaeobius litoreus sp. nov., isolated from a marine solar saltern

Two extremely halophilic archaeal strains GX1^T and GX60 were isolated from the Gangxi marine solar saltern, China. Cells from the two strains were observed to be rod-shaped and stained Gram-negative, with red-pigmented colonies. Strains GX1^T and GX60 were found to be able to grow at 25–50 °C (optimum 37 °C), at 1.4–4.8 M NaCl (optimum 2.6 M), at pH 5.5–9.5 (optimum pH 7.0) and neither strain required Mg²⁺ for growth. The cells lysed in distilled water and the minimal NaCl concentration to prevent cell-lysis was found to be 8 % (w/v). The major polar lipids of the two strains were identified as phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and three glycolipids chromatographically identical to those of Haloarchaeobius iranensis IBRC-M 10013^T. 16S rRNA gene analysis revealed that each strain had two dissimilar 16S rRNA genes and both strains were phylogenetically related to Hab. iranensis IBRC-M 10013^T (94.9–98.9 % nucleotide identity). The rpoB′ gene similarity between strains GX1^T and GX60, and between these strains and Hab. iranensis IBRC-M 10013^T were found to be 99.6, 96.0 and 95.8 %, respectively. The DNA G + C content of strain GX1^T and GX60 were determined to be 67.7 and 67.8 mol %, respectively. The DNA–DNA hybridization value of strains GX1^T and GX60 was 86 % and the two strains showed low DNA–DNA relatedness with Hab. iranensis IBRC-M 10013^T (38 and 32 %). It was concluded that strain GX1^T (= CGMCC 1.10390^T = JCM 17114^T) and strain GX60 (= CGMCC 1.10389 = JCM 17120) represent a new species of Haloarchaeobius, for which the name Haloarchaeobius litoreus sp. nov. is proposed.